1. Field of the Invention
The present invention relates to a method for smelting reduction of iron ore and an apparatus therefore, and particularly to a method and an apparatus wherein iron ore is being smelted and reduced in a basic oxygen furnace type vessel.
2. Description of Prior Arts
Smelting reduction method has recently been developed as a substitution for a blast furnace iron-making method, to overcome some disadvantages in that the blast furnace iron-making method requires not only an expensive construction cost but also a vast construction site.
In a prior art smelting reduction method, iron ore is prereduced by means of an exhaust gas, and then the prereduced iron ore is charged together with carbonaceous material and flux into a smelting reduction furnace. Furthermore, oxygen gas and stirring gas are blown into the smelting reduction furnace. The carbonaceous material is dissolved into molten metal charged in advanced and, at the same time, C contained in the carbonaceous materials is oxidated by the oxygen gas. Through the heat produced by this oxidation, the iron ore is smelted and reduced by means of C contained in the carbonaceous material to form molten metal bath. CO gas generating from the molten metal bath is post-combusted, by the oxygen gas excessively blown in, into CO.sub.2 gas. The sensible heat of this CO.sub.2 gas is transferred to a slag layer and iron particles in the slag layer covering the surface of the molten metal bath, and then, to the molten metal bath.
In this manner, the iron ore is reduced into the molten metal. To lighten the load of the reduction in the smelting reduction furnace, the iron ore is prereduced upto a reduction degree of 60 to 75% before the iron ore is charged into the smelting reduction furnace. Therefore, an exhaust gas generating from the smelting reduction furnace is required to be a low oxidated gas which is highly reductive and to also be of a large amount.